+ char *out, *ret;
+ out = ret = snewn(strlen(in)+1, char);
+ while (*in) {
+ if (*in == '%' && in[1] && in[2]) {
+ int i, j;
+
+ i = in[1] - '0';
+ i -= (i > 9 ? 7 : 0);
+ j = in[2] - '0';
+ j -= (j > 9 ? 7 : 0);
+
+ *out++ = (i << 4) + j;
+ in += 3;
+ } else {
+ *out++ = *in++;
+ }
+ }
+ *out = '\0';
+ return ret;
+}
+
+static char *make_filename(int index, const char *subname)
+{
+ char *env, *tmp, *ret;
+
+ /*
+ * Allow override of the PuTTY configuration location, and of
+ * specific subparts of it, by means of environment variables.
+ */
+ if (index == INDEX_DIR) {
+ struct passwd *pwd;
+
+ env = getenv("PUTTYDIR");
+ if (env)
+ return dupstr(env);
+ env = getenv("HOME");
+ if (env)
+ return dupprintf("%s/.putty", env);
+ pwd = getpwuid(getuid());
+ if (pwd && pwd->pw_dir)
+ return dupprintf("%s/.putty", pwd->pw_dir);
+ return dupstr("/.putty");
+ }
+ if (index == INDEX_SESSIONDIR) {
+ env = getenv("PUTTYSESSIONS");
+ if (env)
+ return dupstr(env);
+ tmp = make_filename(INDEX_DIR, NULL);
+ ret = dupprintf("%s/sessions", tmp);
+ sfree(tmp);
+ return ret;
+ }
+ if (index == INDEX_SESSION) {
+ char *munged = mungestr(subname);
+ tmp = make_filename(INDEX_SESSIONDIR, NULL);
+ ret = dupprintf("%s/%s", tmp, munged);
+ sfree(tmp);
+ sfree(munged);
+ return ret;
+ }
+ if (index == INDEX_HOSTKEYS) {
+ env = getenv("PUTTYSSHHOSTKEYS");
+ if (env)
+ return dupstr(env);
+ tmp = make_filename(INDEX_DIR, NULL);
+ ret = dupprintf("%s/sshhostkeys", tmp);
+ sfree(tmp);
+ return ret;
+ }
+ if (index == INDEX_HOSTKEYS_TMP) {
+ tmp = make_filename(INDEX_HOSTKEYS, NULL);
+ ret = dupprintf("%s.tmp", tmp);
+ sfree(tmp);
+ return ret;
+ }
+ if (index == INDEX_RANDSEED) {
+ env = getenv("PUTTYRANDOMSEED");
+ if (env)
+ return dupstr(env);
+ tmp = make_filename(INDEX_DIR, NULL);
+ ret = dupprintf("%s/randomseed", tmp);
+ sfree(tmp);
+ return ret;
+ }
+ tmp = make_filename(INDEX_DIR, NULL);
+ ret = dupprintf("%s/ERROR", tmp);
+ sfree(tmp);
+ return ret;
+}
+
+void *open_settings_w(const char *sessionname, char **errmsg)
+{
+ char *filename;
+ FILE *fp;
+
+ *errmsg = NULL;
+
+ /*
+ * Start by making sure the .putty directory and its sessions
+ * subdir actually exist.
+ */
+ filename = make_filename(INDEX_DIR, NULL);
+ if (mkdir(filename, 0700) < 0 && errno != EEXIST) {
+ *errmsg = dupprintf("Unable to save session: mkdir(\"%s\") "
+ "returned '%s'", filename, strerror(errno));
+ sfree(filename);
+ return NULL;
+ }
+ sfree(filename);
+
+ filename = make_filename(INDEX_SESSIONDIR, NULL);
+ if (mkdir(filename, 0700) < 0 && errno != EEXIST) {
+ *errmsg = dupprintf("Unable to save session: mkdir(\"%s\") "
+ "returned '%s'", filename, strerror(errno));
+ sfree(filename);
+ return NULL;
+ }
+ sfree(filename);
+
+ filename = make_filename(INDEX_SESSION, sessionname);
+ fp = fopen(filename, "w");
+ if (!fp) {
+ *errmsg = dupprintf("Unable to save session: open(\"%s\") "
+ "returned '%s'", filename, strerror(errno));
+ sfree(filename);
+ return NULL; /* can't open */
+ }
+ sfree(filename);
+ return fp;